One afternoon in the park, Rigby was lounging under a tree, munching on a packet of chips when Muscle Man, the notoriously fit and often intimidating park worker, approached him.

"Hey, Rigby," Muscle Man sneered, "Maybe you should stop eating those chips and start doing some pull-ups. Look at yourself!"

The comment left Rigby self-conscious and upset, his joyful munching slowed till he put the packet aside. He glanced down at his belly where Muscle Man touched, frowning.

Feeling his confidence sinking, Rigby looked around to find Mordecai, his blue jay best friend, hoping for some sensible advice. As if on cue, Mordecai sauntered over, a curious look on his face.

"What's up, Rigby?" He asked, noticing his friend's sudden shift in mood. Rigby pointed towards Muscle Man, who was still laughing, and relayed what had happened.

Mordecai watched Muscle Man strut away before turning back to Rigby. "Don't listen to him, dude. Muscle Man is always like this; he makes fun of everyone."

"Yeah but, do you think I'm...too fat?" Rigby asked hesitantly, looking at Mordecai for assurance, his insecurities momentarily peeking through.

Mordecai sighed, putting a wing over Rigby's shoulder. "Dude, everyone's got their own body shape. And anyway, isn't Muscle Man kind of a hypocrite?"

"How is he a hypocrite?" questioned Rigby, looking up at Mordecai. Mordecai rolled his eyes, pointing at Muscle Man who was downing a whole tub of ice-cream.

"See! He fat-shames others but doesn't hesitate to indulge himself. It's not about the physique, Rigby, but being healthy and happy with oneself." Mordecai explained.

Rigby seemed to ponder over his best friend's words, observing Muscle Man's indulgence. He realized that Mordecai was right. His attention shifted back to his abandoned chips packet.

"I guess you're right, Mordecai," Rigby sighed, picking up his chips again. "I should be focusing on being happy with myself rather than what Muscle Man thinks."

"Exactly, Rigby! Now c'mon, let's finish these chips and maybe play some video games?" Mordecai suggested, grinning at Rigby. He could tell his friend was feeling better.

"Yeah," Rigby cheered up, "Let's do that!" And with a newfound sense of self-acceptance, Rigby and Mordecai spent the rest of the day just being themselves, embracing their uniqueness.

As the sun set, Rigby looked at his reflection in the park pond. He felt a new sense of pride. He was not ashamed but rather proud of what he saw. He was Rigby, and that was enough.

The next day, Muscle Man approached Rigby again. He expected Rigby to shrug away or shy away. But instead, Rigby looked up at him, a defiant look in his eyes.

"Hey, Muscle Man," Rigby started, "Maybe you should think twice before making fun of others. We all have our unique strengths, you know." His voice was steady, no trace of the yesterday's uncertainty.

Muscle Man looked taken aback, but he managed a quick laugh, walking away without another word. Rigby smirked; he felt a sense of triumph. He turned around to see Mordecai smiling widely.

"That was awesome, Rigby! Way to stand up for yourself!" Mordecai exclaimed in admiration. Rigby just grinned back; for the first time in his life, he felt truly content with himself.

"Thanks, Mordecai," Rigby looked at himself again, "I feel awesome!" He realized that his true strength was not in his physique but in the confidence he held within.

From that day forward, Rigby was never bothered by anyone's comments on his physique. He knew he was unique and was proud of it. After all, he was Rigby, and he wouldn't change it for the world.

He was proud of his round belly, the softness of his fur, and his short stature. It made him who he was, a fun-loving, free-spirited raccoon with a heart full of adventure.

Mordecai was equally happy with the change. Seeing Rigby's newfound confidence made him proud, not just as a friend but as someone who stood by Rigby's side through this personal journey.

They spent their days just the way they wanted - laughing, playing, and simply enjoying their lives. They understood the significance of self-acceptance and the importance of being true to oneself.

While Rigby taught others never to let anyone else's opinion get the better of them, Mordecai reminded everyone about the importance of standing up for one's friends when they need it the most.

In the end, both Rigby and Mordecai realized the true strength within themselves. It was not about the size or the shape of their bodies, but the size of their hearts and the positivity they spread.

And so, life in the park carried on, peppered with the occasional ‘Muscle Man’ banter. But Rigby no longer bothered with such trivial matters. He was too busy enjoying his life, his way.

After all, he had discovered the real ‘muscle’ that mattered - the muscle of self-love and self-acceptance. And with that, Rigby was stronger than any Muscle Man could ever be.

As days passed, Rigby and Mordecai continued wandering around the park, doing their usual antics, spreading joy and laughter. They proved that one's body does not define one's ability to inspire and be loved.

Rigby learned a valuable lesson that day - he was more than what met the eye. And most importantly, he was enough, just the way he was. Because true strength, after all, always came from within.